The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
David J. Burinsky - One of the best experts on this subject based on the ideXlab platform.
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Hybrid mass Spectrometers for tandem mass spectrometry
Journal of the American Society for Mass Spectrometry, 2008Co-Authors: Gary L Glish, David J. BurinskyAbstract:Mass Spectrometers that use different types of analyzers for the first and second stages of mass analysis in tandem mass spectrometry (MS/MS) experiments are often referred to as “hybrid” mass Spectrometers. The general goal in the design of a hybrid instrument is to combine different performance characteristics offered by various types of analyzers into one mass Spectrometer. These performance characteristics may include mass resolving power, the ion kinetic energy for collision-induced dissociation, and speed of analysis. This paper provides a review of the development of hybrid instruments over the last 30 years for analytical applications.
Denis J Phares - One of the best experts on this subject based on the ideXlab platform.
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a comparison of particle mass Spectrometers during the 1999 atlanta supersite project
Journal of Geophysical Research, 2003Co-Authors: Ann M. Middlebrook, Ryan J Wenzel, Denis J Phares, D M Murphy, D S Thomson, Kimberly A. PratherAbstract:During the Atlanta Supersite Project, four particle mass Spectrometers were operated together for the first time: NOAA's Particle Analysis by Laser Mass Spectrometer (PALMS), University of California at Riverside's Aerosol Time-of-Flight Mass Spectrometer (ATOFMS), University of Delaware's Rapid Single-Particle Mass Spectrometer II (RSMS-II), and Aerodyne's Aerosol Mass Spectrometer (AMS). Although these mass Spectrometers are generally classified as similar instruments, they clearly have different characteristics due to their unique designs. One primary difference is related to the volatilization/ionization method: PALMS, ATOFMS, and RSMS-II utilize laser desorption/ionization, whereas particles in the AMS instrument are volatilized by impaction onto a heated surface with the resulting components ionized by electron impact. Thus mass spectral data from the AMS are representative of the ensemble of particles sampled, and those from the laser-based instruments are representative of individual particles. In addition, the AMS instrument cannot analyze refractory material such as soot, sodium chloride, and crustal elements, and some sulfate or water-rich particles may not always be analyzed with every laser-based instrument. A main difference among the laser-based mass Spectrometers is that the RSMS-II instrument can obtain size-resolved single particle composition information for particles with aerodynamic diameters as small as 15 nm. The minimum sizes analyzed by ATOFMS and PALMS are 0.2 and about 0.35 μm, respectively, in aerodynamic diameter. Furthermore, PALMS, ATOFMS, and RSMS-II use different laser ionization conditions. Despite these differences the laser-based instruments found similar individual particle classifications, and their relative fractions among comparable sized particles from Atlanta were broadly consistent. Finally, the AMS measurements of the nitrate/sulfate mole ratio were highly correlated with composite measurements (r^2 = 0.93). In contrast, the PALMS nitrate/sulfate ion ratios were only moderately correlated (r^2 ∼ 0.7).
Antonio Plaza - One of the best experts on this subject based on the ideXlab platform.
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Spectrometer-Driven Spectral Partitioning for Hyperspectral Image Classification
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2016Co-Authors: Jun Li, Antonio PlazaAbstract:Classification is an important and widely used technique for remotely sensed hyperspectral data interpretation. Although most techniques developed for hyperspectral image classification assume that the spectral signatures provided by an imaging Spectrometer can be interpreted as a unique and continuous signal, in practice, this signal may be obtained after the combination of several individual responses obtained from different Spectrometers. In this work, we propose a new spectral partitioning strategy prior to classification which takes into account the physical design of the imaging Spectrometer system for partitioning the spectral bands collected by each Spectrometer, and resampling them into different groups or partitions. The final classification result is obtained as a combination of the results obtained from each individual partition by means of a multiple classifier system (MCS). The proposed strategy not only incorporates the design of the imaging Spectrometer into the classification process but also circumvents problems such as the curse of dimensionality given by the unbalance between the high number of spectral bands and the generally limited number of training samples available for classification purposes. This concept is illustrated in this work using two different imaging Spectrometers: the airborne visible infra-red imaging Spectrometer, operated by NASA, and the digital airborne imaging system (DAIS), operated by the German Aerospace Center. Our experiments indicate that the proposed spectral partitioning strategy can lead to classification improvements on the order of 5% overall accuracy when using state-of-the-art spatial-spectral classifiers with very limited training samples.
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Spectrometer-driven spectral partitioning for hyperspectral image classification
2014 6th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (WHISPERS), 2014Co-Authors: Jun Li, Antonio Plaza, Peijun Du, Mahdi KhodadadzadehAbstract:Classification is an important and widely used technique for remotely sensed hyperspectral data interpretation. Although most techniques developed for classification assume that the spectral signatures provided by an imaging Spectrometer can be interpreted as a unique and continuous signal, in practice this signal may be obtained after the combined individual responses from several different Spectrometers. For instance, the Airborne Visible Infra-Red Imaging Spectrometer (AVIRIS) system is in fact formed by four different Spectrometers, covering the nominal spectral ranges of 400-700 nm, 700-1300 nm, 1300-1900 nm, and 1900-2500 nm, respectively. In this work, we propose a new classification strategy which takes into account the physical design of the imaging Spectrometer system for partitioning the spectral bands collected by each Spectrometer, and resampling them into different groups or partitions. The final classification result is obtained as a combination of the results obtained from each individual partition. This concept is illustrated in this work using AVIRIS data, and our experimental results indicate that the proposed strategy provides advantages in terms of classification accuracy, in particular, when very limited training samples are available.
Alexander F H Goetz - One of the best experts on this subject based on the ideXlab platform.
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the spectral image processing system sips interactive visualization and analysis of imaging Spectrometer data
Remote Sensing of Environment, 1993Co-Authors: Fred A Kruse, A B Lefkoff, J Boardman, K B Heidebrecht, A T Shapiro, P J Barloon, Alexander F H GoetzAbstract:Abstract The Center for the Study of Earth from Space (CSES) at the University of Colorado, Boulder, has developed a prototype interactive software system called the Spectral Image Processing System (SIPS) using IDL (the Interactive Data Language) on UNIX-based workstations. SIPS is designed to take advantage of the combination of high spectral resolution and spatial data presentation unique to imaging Spectrometers. It streamlines analysis of these data by allowing scientists to rapidly interact with entire datasets. SIPS provides visualization tools for rapid exploratory analysis and numerical tools for quantitative modeling. The user interface is X-Windows-based, user friendly, and provides “point and click” operation. SIPS is being used for multidisciplinary research concentrating on use of physically based analysis methods to enhance scientific results from imaging Spectrometer data. The objective of this continuing effort is to develop operational techniques for quantitative analysis of imaging Spectrometer data and to make them available to the scientific community prior to the launch of imaging Spectrometer satellite systems such as the Earth Observing System (EOS) High Resolution Imaging Spectrometer (HIRIS).
Wei Xu - One of the best experts on this subject based on the ideXlab platform.
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A mini mass Spectrometer with a low noise Faraday detector.
The Analyst, 2020Co-Authors: Yang Tang, Dayu Li, Qian Xu, Wei XuAbstract:An ion trap mass Spectrometer is conventionally featured with an electron multiplier as its detector. However, an electron multiplier can typically work at pressures below 20 mTorr with a high voltage applied, which limits the further miniaturization of ion trap mass Spectrometers. In this work, a low noise Faraday detector was developed and integrated in our miniature mass Spectrometer instrument, and a post data processing method was applied to improve its performance. A limit of detection of 1 ng mL-1 was achieved, and quantitation performance and mass resolution were characterized. This technology could be useful in the further development of miniature mass Spectrometers by increasing background pressures.
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Recent developments of miniature ion trap mass Spectrometers
Chinese Chemical Letters, 2017Co-Authors: Yanbing Zhai, Wei XuAbstract:Abstract With outstanding analytical performance and portability, miniature mass Spectrometer is one of the most powerful tools for in-situ analysis. The miniaturization of mass Spectrometers has lasted for more than ten years, during which a number of miniature mass Spectrometers employing different techniques have been developed. Small-in-size, working at relatively high pressure region and capable of performing tandem mass spectrometry, ion trap is the most widely used mass analyzer in miniature mass Spectrometer systems. The recent development of miniature ion trap mass Spectrometer systems in the last ten years was reviewed in this paper. These instruments adopt different atmospheric pressure interfaces (APIs), which are membrane inlets (MIs), discontinuous atmospheric pressure interface (DAPI) and continuous atmospheric pressure interface (CAPI). This review emphasizes on the mini mass spectrometry (MS) system that can be handheld by one person, but not the field-able ones that are too large to be hand-portable.
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Development of a miniature mass Spectrometer with in-source desolvation
International Journal of Mass Spectrometry, 2016Co-Authors: Yan Chen, Muyi He, Xingchuang Xiong, Xiang Fang, Yonggang Zhao, Wei XuAbstract:Abstract Miniature mass Spectrometers could meet the on-site chemical analysis requirements in applications such as space exploration, homeland security, etc. However, miniaturization of a mass Spectrometer would sacrifice its performance due to simplified instrumentation and limitations on power and size. In this study, in-source desolvation capability was developed for a miniature mass Spectrometer. Similar to the conventional in-source fragmentation technique, the in-source desolvation is more gentle, which is designed to fragment clusters and droplets other than ions. In-source desolvation could effectively help the desolvation of droplets generated by electrospray ionization, and both signal intensity and signal-to-noise ratio of a mass peak could be increased. As a result, sensitivity improvement could be achieved for the miniature mass Spectrometer. Compared to the desolvation techniques used on a lab-scale instrument (heated interface, desolvation gas, for instance), the in-source desolvation method is more suitable and economic for a miniature mass Spectrometer.
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Sampling wand for an ion trap mass Spectrometer.
Analytical Chemistry, 2011Co-Authors: Wei Xu, Jian Xu, R. Graham Cooks, Zheng OuyangAbstract:A new sampling wand concept for ion trap mass Spectrometers equipped with discontinuous atmospheric pressure interfaces (DAPI) has been implemented. The ion trap/DAPI combination facilitates the operation of miniature mass Spectrometers equipped with ambient ionization sources. However, in the new implementation, instead of transferring ions pneumatically from a distant source, the mass analyzer and DAPI are separated from the main body of the mass Spectrometer and installed at the end of a 1.2 m long wand. During ion introduction, ions are captured in the ion trap while the gas in which they are contained passes through the probe and is pumped away. The larger vacuum volume due to the extended wand improves the mass analysis sensitivity. The wand was tested using a modified hand-held ion trap mass Spectrometer without additional power or pumping being required. Improved sensitivity was obtained as demonstrated with nano-electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and l...
